Throughout various industrial applications, apparatus components are subjected to numerous extreme conditions (e.g., high temperatures, high pressures, large stress loads, etc.). Over time, an apparatus's individual components may suffer creep and/or deformation that may reduce the component's usable life. Such concerns might apply, for instance, to some turbomachines.
Turbomachines are widely utilized in fields such as power generation and aircraft engines. For example, a conventional gas turbine system includes a compressor section, a combustor section, and at least one turbine section. The compressor section is configured to compress air as the air flows through the compressor section. The air is then flowed from the compressor section to the combustor section, where it is mixed with fuel and combusted, generating a hot gas flow. The hot gas flow is provided to the turbine section, which utilizes the hot gas flow by extracting energy from it to power the compressor, an electrical generator, and other various loads.
During operation of a turbomachine, various components within the turbomachine and particularly within the turbine section of the turbomachine, such as turbine blades, may be subject to creep due to high temperatures and stresses. For turbine blades, creep may cause portions of or the entire blade to elongate so that the blade tips contact a stationary structure, for example a turbine casing, and potentially cause unwanted vibrations and/or reduced performance during operation.
Accordingly, it is desirable to monitor components for creep. One approach to monitoring components for creep is to configure strain sensors on the components, and analyze the strain sensors at various intervals to monitor for deformations associated with creep strain. However, such deformation can in many cases be on the order of 0.01% of an original dimension, thus requiring specialized equipment for strain monitoring. Such equipment in many cases requires precise calibrations which are not feasible in situ.
For instance, specialized equipment may be used to obtain visual images of the strain sensors, and compare the dimensions of the strain sensors in images taken at varying times for an associated component. Typically, dimensions along two axes can be directly measured in such images, while dimensions along a third axis may be inferred. However, such approaches generally require a direct line of sight to the sensor and component. A great deal of space and disassembly may be required in order to measure the component. As a result, in situ measurements can be difficult, if not impossible with most existing systems.